Project 2 - Digital Amplification (for headphones?)
Aug 29, 2003 at 1:15 AM Post #16 of 23

aos

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Quote:

comes only partially assembled. It doesn't work without the end user modifying it a bit, so it's not needed as I understand it.


Yep, that's the trick around it. If it's a sub-assembly, you need not get an approval
smily_headphones1.gif
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Quote:

if your stuff is sold in the US, it is supposed to be FCC cert


That's a gray area I think. I've read the laws on our local BC government webiste for under what conditions do they require non-BC based companies to pay provincial sales tax on behalf of BC customers - similar situation to as when does the FCC apply. Basically as long as you allow their citizens to buy it, you should tax them on the behalf of their goverment. There are companies worth billion+ dollars that don't bother and since they don't have offices in BC, it's not possible for government to enforce the law. Basically most small and many big mail (or internet) order companies in the world are violating the law of the country which citizens they sell to. E.g. if I sell something to a guy in California, I should collect state sales tax and pay it. When companies say the tax only applies to local purchasers it's because the goverment there has the jurisdiction to go after them, not because there's no tax if you buy from out of state (at least it's the case in many states / countries). Anyhow...

Quote:

I play with Tesla coils and those things violate every FCC reg. there is, but then again I don't sell them.


I actually don't think that would count as an excuse - just as building your own antenna and transmitter and turning it on is going to get you in trouble with them even though you're not selling that
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Aug 29, 2003 at 1:31 AM Post #17 of 23

aos

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TAS5015 is only available with license from equibit. Here's one link to a (now quite old) press release - there are more around the web, including I think Stereophile so this is not a hoax

http://www.3dsoundsurge.com/press/pr1671.html

Chip is actually available but I think the "discrete back end" schematics" isn't, and that is what makes this one better than the competition (or at least that was claimed 2 years ago or something).

http://focus.ti.com/lit/ds/symlink/tas5015.pdf

This document explains a lot about how digital amps work:

http://focus.ti.com/lit/an/slaa117a/slaa117a.pdf
 
Aug 29, 2003 at 2:00 AM Post #18 of 23

rickcr42

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for ultimate fidelity digital amplification is not the way to go , especially for headphone use where resolution is paramount

otherwise why amp the pcdp in the first place ?

the dsp/digital volume/dac is the main weakness of the headphone out

where digital amps shine is in big time power output for subs

at such low freqs the bandwidth filters have zero effect and the power out for voltage in , not to mention heat sink savings are a definate plus
 
Aug 29, 2003 at 2:05 AM Post #19 of 23

aos

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True Rick, most of the digital stuff at the moment is mid-fi, but supposedly this technology from Equibit that TI is licensing is really Hi-Fi. There are some high end manufacturers using these chips. I think it's only going to improve as other manufacturers find their own ways to increase fidelity.

For headphones this stuff is I think too much (power AND noise) right now.
 
Aug 29, 2003 at 5:46 PM Post #20 of 23

maczrool

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Quote:

Originally posted by aos



I actually don't think that would count as an excuse - just as building your own antenna and transmitter and turning it on is going to get you in trouble with them even though you're not selling that
smily_headphones1.gif
.


The thing is, operation is very sporatic. They'd never find it in operation. As an FIY, my avatar is a picture of part of the Tesla coil power supply I use.

Quote:

For headphones this stuff is I think too much (power AND noise) right now.


Not really. Some of them are very low noise. Not relative to top DAC IC specs, that's true, but to other amps, it's very commendable. Power consumption is low too. Using some of TI's amp ICs in concert with their PWM processors would probably reduce the component count over an analog DAC/headphone amp as well.

Stu
 
Jan 18, 2008 at 10:18 PM Post #22 of 23

greyhorse

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For those of you interested, Sony recently released a High-End integrated SACD/digital-amplifier player for the Japanese market. This product is part of Sony's Qualia line which, AFAIK, isn't sold at normal stores but only at special Sony showrooms.

For a little background info, the Qualia project was started by the previous Sony president to showcase what is currently possible at the cutting-edge. With the current trend towards making cost-oriented products, Sony was seeing decline sales. The Qualia project was supposed to be a return to the Sony of old, where products were design driven. To this end all product departments were asked to come up with a cost-no-object design that customers would really want to buy.

The "special" feature for this player is an automatic centering mechanism that allows the user to simply drop the CD somewhere in the loading area. The CD is then centered and raised by 3 shiny pillars (machined to 0.05mm tolerance). The transport mechanism then sandwitches the CD and playback begins. The motorized clear plastic top panel adds additional oooh factor but does little else. The player retails for around US$6900. The attached picture shows the digital amplifier section of player which puts out 100Wpch into a 6ohm load.

To download the catalog go here: http://www.sony.jp/products/Consumer...p/slot_05.html
and click on the left-most arrow underneath the pretty picture. Be carefull though, 'cause it's a 2.46MB file.
 

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